JP2005178125A - Droplet ejection head and droplet ejection apparatus provided with a droplet ejection head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid droplet discharge head which can make a print quality highly precise by preventing the dispersion of the discharge level of a liquid from the liquid droplet discharge head from occurring, and a liquid droplet discharge device equipped with the liquid droplet discharge head. <P>SOLUTION: In the liquid droplet discharge head 1, a plurality of liquid intakes 31 for the liquid droplet discharge head 1 are provided and thereby, the liquid level accumulated in each pressure chamber 6 is constant. Besides, the difference in the pressure fluctuations of the pressure chambers 6 hardly occurs, so that the velocity fluctuations of the liquid discharged from the nozzle 21 can be curbed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a droplet discharge head of a droplet discharge device. More specifically, the present invention relates to a structure of a droplet discharge head that reduces variations in the amount of liquid discharged between nozzles, and a droplet discharge device that includes the droplet discharge head.

  2. Description of the Related Art In recent years, various types of droplet discharge heads of a droplet discharge apparatus are known depending on a mechanism for generating (discharge) droplets. For example, there is a droplet discharge head of a type in which a heater is heated to boil a liquid and a droplet is discharged with a bubble pressure generated thereby. In addition, there is a droplet discharge head of a type that discharges droplets by expanding and contracting the volume of a pressure chamber by applying a voltage to a piezoelectric element attached to a pressure chamber that stores liquid. Further, there is a type in which droplets are discharged by changing the volume of a pressure chamber in which liquid is stored using electrostatic force. In any type of droplet ejection head, droplets are ejected only when necessary for recording using the pressure fluctuation in the pressure chamber.

  These types of droplet discharge heads are generally arranged corresponding to each of a plurality of nozzles, and supply pressure to each pressure chamber and a pressure chamber for discharging droplets from the corresponding nozzle by pressure fluctuation. Each of the pressure chambers has a reservoir and a liquid supply port communicating with the reservoir. It is known that the pressure chamber, the reservoir, and the liquid supply port have a configuration of a droplet discharge head that is partitioned and formed in a state of being arranged in a plane direction between these substrates by superimposing flat substrates (see FIG. For example, see Patent Document 1).

JP-A-11-115179

  However, in the conventional droplet discharge head, when a pressure fluctuation is generated in the pressure chamber in order to discharge the droplet, the liquid is positioned at both ends of the droplet discharge head when the liquid is sequentially supplied from the reservoir through the liquid supply port. In the pressure chamber and the pressure chamber located in the central portion, there is a problem in that the difference in the flow rate of the liquid in the reservoir and the amount of the liquid supplied from the liquid supply port to the pressure chamber due to this vary. As a result, a difference also occurs in the pressure fluctuation in the pressure chamber, and a difference occurs in the speed of the liquid ejected from the nozzle. Therefore, there are problems such as variations in the amount of liquid ejected from the nozzles located in the droplet ejection head, and inaccurate print quality due to variations in the liquid ejection speed.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, prevent variation in the amount of liquid discharged by the nozzle position of the droplet discharge head, and enable a highly accurate print quality and a droplet discharge head. A droplet discharge device comprising:

  The droplet discharge head according to the present invention is arranged corresponding to each of a plurality of nozzles for discharging liquid between the first substrate and the second substrate by overlapping each other. Pressure chambers that discharge liquid from corresponding nozzles, reservoirs that supply liquids to the pressure chambers, and a plurality of liquid supply ports that communicate the pressure chambers with the reservoirs are arranged in a planar direction. A plurality of liquid inlets that are partitioned and have liquid inlets for injecting liquid into the reservoir, so that the difference in distance between the liquid inlets and the closest liquid inlets is within 10%. It is provided.

  According to the present invention, by providing a plurality of liquid intake ports for injecting liquid into the reservoir so that the distance between each intake port is 10% or less between each liquid supply port and the closest liquid intake port. The difference in liquid flow rate between the pressure chambers located at both ends of the droplet discharge head in the reservoir and the pressure chamber located at the center is almost eliminated. In other words, the amount of liquid supplied through each liquid supply port communicating with the reservoir is substantially constant, and thus the amount of liquid accumulated in each pressure chamber is substantially constant. Moreover, since the difference in pressure fluctuations in the pressure chambers is less likely to occur, fluctuations in the speed of the liquid ejected from the nozzles can be suppressed. Further, the amount of droplets ejected from each nozzle of the droplet ejection head is also substantially constant.

  In the liquid droplet ejection head of the present invention, it is desirable that the plurality of liquid intake ports be arranged at least in a straight line.

  According to this invention, since the plurality of liquid intake ports are arranged at least in a straight line, the difference in distance between the liquid intake port and the liquid supply port is reduced, so that the amount of liquid supplied is substantially constant. As a result, the amount of liquid accumulated in each pressure chamber becomes more constant. Moreover, since the difference in pressure fluctuations in the pressure chambers is less likely to occur, fluctuations in the speed of the liquid ejected from the nozzles can be suppressed. Further, the amount of droplets ejected from each nozzle of the droplet ejection head is also more constant.

  The droplet discharge head according to the present invention is arranged corresponding to each of a plurality of nozzles for discharging liquid between the first substrate and the second substrate by overlapping each other. The pressure chambers for discharging liquid from the corresponding nozzles, the reservoirs for supplying the liquids to the pressure chambers, and the liquid supply ports for communicating the pressure chambers with the reservoirs are partitioned in the plane direction. And a liquid intake port for injecting liquid into the reservoir. The liquid intake port has a long hole shape and is formed so that a difference in distance from each liquid supply port is within 10%. To do.

  According to the present invention, since the liquid intake port has a long hole shape and the difference in distance from each liquid supply port is within 10%, the difference in distance between the liquid intake port and the liquid supply port. Therefore, the distribution of the flow velocity of the liquid becomes almost constant, and the amount of the supplied liquid is adjusted with high accuracy, so that the amount of the liquid accumulated in each pressure chamber is managed almost uniformly. Moreover, since the difference in pressure fluctuations in the pressure chambers is less likely to occur, fluctuations in the speed of the liquid ejected from the nozzles can be suppressed. Further, the amount of droplets ejected from each nozzle of the droplet ejection head is also substantially uniform.

  The droplet discharge head of the present invention is preferably provided so that the longitudinal direction of the liquid intake port is parallel to the arrangement direction of the liquid supply ports.

  According to this invention, since the longitudinal direction of the liquid intake port is provided so as to be parallel to the arrangement direction of the liquid supply ports, the difference in the distance between the liquid intake port and the liquid supply port is reduced. Accordingly, the distribution of the flow velocity of the liquid becomes more constant, and the amount of the supplied liquid is adjusted with high accuracy, so that the amount of the liquid accumulated in each pressure chamber is managed more uniformly. Moreover, since the difference in pressure fluctuations in the pressure chambers is less likely to occur, fluctuations in the speed of the liquid ejected from the nozzles can be suppressed. Further, the amount of droplets ejected from each nozzle of the droplet ejection head is also more uniform.

  The droplet discharge device of the present invention is desirably a droplet discharge device including the above-described droplet discharge head.

  According to this invention, since the droplet discharge device includes the above-described droplet discharge head, high-precision print quality can be obtained. Therefore, it is possible to provide a droplet discharge device that can obtain such an effect.

  Hereinafter, embodiments of a droplet discharge head and a droplet discharge apparatus including the droplet discharge head according to the present invention will be described in detail with reference to the accompanying drawings.

[First Embodiment]
FIG. 1 is an exploded perspective view showing a part of a droplet discharge head as a first embodiment of the present invention. FIG. 2 is a cross-sectional view of the droplet discharge head. FIG. 3 is a plan view of the cavity plate.

  As shown in FIGS. 1 and 2, the droplet discharge head 1 is a face ink jet type that discharges ink droplets from a nozzle provided on the upper surface of a substrate, and is of an electrostatic drive type. The droplet discharge head 1 has a laminated structure in which a nozzle plate (first substrate) 2, a cavity plate (second substrate) 3, and a glass substrate 4 are bonded together in this order.

  The cavity plate 3 is, for example, a silicon substrate. As shown in FIGS. 1 to 3, the cavity plate 3 has a recess 7 that forms a pressure chamber 6 whose bottom wall functions as the diaphragm 5 on the surface of the cavity plate 3. The narrow groove 9 constituting the ink supply port 8 provided in the rear part of the recess 7 and the recess 11 constituting the ink reservoir 10 for supplying ink to each pressure chamber 6 are etched. Is formed by. The lower surface of the cavity plate 3 is smoothed by mirror polishing and serves as a mounting portion for the glass substrate 4.

  As shown in FIGS. 1 and 2, in the nozzle plate 2 joined to the upper surface of the cavity plate 3 (the substrate surface on the groove forming side), the wall portion defining the upper surface of the pressure chamber 6 is provided in each pressure chamber 6. A plurality of nozzles 21 communicating with each other are formed. As shown in FIG. 2, the nozzle 21 has a step-like cross section, and a circular small cross-section nozzle portion 21a is formed on the front side (upper side in the figure) of the ink droplet 23 in the ejection direction, and on the rear side. A circular large-section nozzle portion 21b is formed.

  By overlapping the nozzle plate 2 and the cavity plate 3 with each other, the pressure chamber 6, the ink supply port 8, and the ink reservoir 10 are arranged in the plane direction H between the nozzle plate 2 and the cavity plate 3. Partitioned into a state.

  In the nozzle plate 2, a plurality of ink intake ports 31 are formed in a wall portion corresponding to the bottom surface of the ink reservoir 10. The ink intake port 31 communicates with the ink reservoir 10 and is connected to a connection pipe 32. The connection pipe 32 is connected to an ink supply source of the ink tank 101 (see FIG. 4) via a tube 33. Ink can be supplied from the ink tank 101 to the ink reservoir 10 via the ink intake port 31.

  In the glass substrate 4, concave portions 13 that constitute the vibration chambers 12 are formed in portions facing the respective vibration plates 5. An individual electrode 14 that faces the diaphragm 5 is disposed on the bottom surface of the recess 13. The individual electrode 14 is connected to the terminal portion 16 via the lead portion 15. The individual electrodes 14 and the lead portions 15 except for the terminal portions 16 are covered with an insulating film 17. A lead wire 18 is bonded to each terminal portion 16. The lead wire 18 is connected to the driver 20 and is configured to be supplied with voltage from the outside (not shown).

Here, the nozzle plate 2 as the first substrate has a plurality of ink intake ports 31. The plurality of ink intake ports 31 communicate with the ink reservoir 10 and are formed to be arranged in a line according to the arrangement direction of the nozzles 21 of the ink reservoir 10 as shown in FIG. A plurality of ink intake ports 31 are provided so that the maximum difference in distance from the ink supply port 8 is within 10%. Here, the distance between the ink supply port 8 and the ink intake port 31 is the outer peripheral end portion of the ink intake port 31 closest to the ink supply port 8.
In addition, a plurality of the distance difference between the ink intake port 31 and the ink supply port 8 is provided within 10% because the ink passes from the ink reservoir 10 through the ink intake port 31. When each pressure chamber 6 is replenished via the ink supply port 8, the flow of ink is adjusted, and the speed and flow rate of the ink supplied to the pressure chamber 6 are stabilized. This is because the amount of ink supplied to the ink becomes substantially uniform.

  FIG. 4 is a schematic perspective view showing a configuration example of a droplet discharge device (inkjet printer) equipped with the droplet discharge head 1 of the present embodiment. The droplet discharge device 100 includes an ink tank 101, a carriage 102, a platen 103, a recording paper 104, and the like, and the droplet discharge head 1 is mounted on the carriage 102.

  The configuration of the droplet discharge head 1 in the present embodiment is as described above, and the operation thereof will be described with reference to FIGS.

  The droplet discharge device 100 supplies ink from the ink tank 101 while moving the carriage 102 while transporting the recording sheet 104 by the platen 103 and controlling the relative position between the recording sheet 104 and the droplet discharge head 1. Then, by ejecting ink droplets 23 from the droplet ejection head 1, arbitrary characters and images are printed on the recording paper 104.

  As shown in FIGS. 1 and 2, the diaphragm 5 that defines the bottom surface of each pressure chamber 6 formed in the cavity plate 3 functions as a common electrode, and the terminal portion 16 of each common electrode and each individual electrode 14. A driver 20 is connected between the two. When a voltage is applied to the individual electrode 14 by the driver 20, the diaphragm 5 facing the individual electrode 14 to which the voltage is applied vibrates due to electrostatic force, and the pressure in the pressure chamber 6 fluctuates accordingly. Ink droplets 23 are ejected from 21.

  For example, when a positive voltage pulse is applied to charge the surface of the individual electrode 14 to a positive potential, the corresponding lower surface of the diaphragm 5 is charged to a negative potential. Therefore, the diaphragm 5 is attracted by the electrostatic force and bent downward. Next, when the voltage pulse applied to the individual electrode 14 is turned off, the diaphragm 5 returns to the original position. By this returning operation, the internal pressure of the pressure chamber 6 is rapidly increased, and the ink droplet 23 is ejected from the nozzle 21. Then, when the vibration plate 5 is bent downward, ink is supplied from the ink reservoir 10 to the pressure chamber 6 via the ink supply port 8.

  Here, since the plurality of ink intake ports 31 are provided so that the maximum difference in distance between the ink intake port 31 and the ink supply port 8 is within 10%, the ink passes through the ink intake port 31. Then, when each pressure chamber 6 is replenished from the ink reservoir 10 via the ink supply port 8, the flow of ink is adjusted, and the speed and flow rate of the ink supplied to the pressure chamber 6 are stabilized. The amount of ink supplied to each pressure chamber 6 becomes substantially uniform.

  For this reason, ink enters the ink reservoir 10 from a plurality of ink intake ports 31 almost simultaneously, and is supplied to the pressure chamber 6 via the ink supply port 8. At this time, since the maximum difference in distance between the ink intake port 31 and the ink supply port 8 is set to be within 10%, the speed and flow rate of the ink flowing in the ink reservoir 10 are substantially equal. It is controlled to become. Accordingly, the ink is supplied to each pressure chamber 6 almost evenly. That is, the speed and flow rate when ink is supplied to each pressure chamber 6 are adjusted substantially uniformly. At the same time, since the amount of ink supplied to each pressure chamber 6 becomes substantially uniform, pressure fluctuation when applying pressure from the diaphragm 5 to the pressure chamber 6 is suppressed. Variations in the ejection speed of the ejected ink droplets 23 and variations in ejection timing from each nozzle 21 are prevented. As a result, the ink droplets 23 can be discharged almost uniformly from the nozzles 21 of the droplet discharge head 1, thereby preventing deterioration in print quality when printing arbitrary characters and images on the recording paper 104. Will do.

  The ink used in the droplet discharge head 1 is prepared by dissolving or dispersing a surfactant such as ethylene glycol and a dye or pigment in a main solvent or main dispersion medium such as water, alcohol or toluene. Is done. Further, if a heater is provided in the droplet discharge head 1, hot melt ink can be used.

In the first embodiment as described above, the following effects are obtained.
1) Since the maximum distance difference between the ink intake port 31 and the ink supply port 8 is set to be within 10%, the amount of ink supplied to each pressure chamber 6 becomes substantially uniform. As a result, the amount of ink droplets 23 ejected from the nozzles 21 of the droplet ejection head 1 becomes substantially uniform. For this reason, when the droplet discharge head 1 prints an arbitrary character or image on the recording paper 104, high-precision print quality can be obtained.

[Second Embodiment]
Next, 2nd Embodiment of this invention is described based on drawing.
In addition, the same code | symbol is attached | subjected to the component same as the above-mentioned 1st Embodiment, and the component which has the same function, and description is abbreviate | omitted.
FIG. 5 is an exploded perspective view showing a part of a droplet discharge head as a second embodiment. FIG. 6 is a plan view of the droplet discharge head.

  Here, as shown in FIGS. 5 and 6, the droplet discharge head 1 is different from the first embodiment in that the ink intake port 31 has a long hole shape and is provided with one. . That is, the shape of the ink intake port 31 is a long hole and is arranged in a state extending in a direction parallel to the arrangement direction of the nozzles 21 of the ink reservoir 10. The ink intake port 31 has a length over the same range as the arrangement range of the ink supply ports 8 in the arrangement direction of the nozzles 21. In addition, the maximum difference in the distance between the ink intake port 31 and the ink supply port 8 is set to be within 10%.

  The configuration of the droplet discharge head 1 according to the second embodiment of the present invention is as described above, and the operation thereof will be described with reference to FIGS.

  In FIGS. 5 and 6, the ink intake port 31 has a long hole shape, and is provided so that the maximum difference in distance between the ink intake port 31 and the ink supply port 8 is within 10%. When the ink flows through the ink reservoir 10, the distance from the ink intake port 31 to the ink supply port 8 is substantially constant, so that the ink is supplied to the ink supply port 8 almost evenly. That is, when ink is supplied to each pressure chamber 6 via the ink supply port 8, the ink speed and flow rate are adjusted more uniformly. At the same time, since the amount of ink supplied to each pressure chamber 6 becomes uniform, pressure fluctuation when applying pressure from the diaphragm 5 into the pressure chamber 6 is suppressed, and the ink is discharged from the nozzle 21. Thus, variations in the ejection speed of the ink droplets 23 and variations in the ejection timing from each nozzle 21 are prevented.

In the second embodiment as described above, the following effects can be obtained in addition to the effects obtained in the first embodiment.
2) Since the ink intake port 31 is provided in the shape of an elongated hole, the elongated hole shape (length, width) can be formed substantially uniformly according to the arrangement direction of the nozzles 21 of the ink reservoir 10. In addition, an error in the distance between the ink supply port 8 and the ink intake port 31 can be reduced. Accordingly, it is possible to easily provide the droplet discharge head 1 having a stable quality, which is suitable for mass production.

  It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention. A modification is shown below.

<Modification 1>
For example, in the first embodiment, a method in which the ink intake ports 31 of the same size (size) are arranged in a straight line is adopted, but the present invention is not particularly limited to this. For example, the size of the ink intake port 31 is arbitrarily selected, the distance between the ink intake port 31 and the ink supply port 8 is appropriately selected according to the size, and the distance between the ink intake port 31 and the ink supply port 8 is selected. The method of arrange | positioning so that a difference may be less than 10% may be used. That is, when the size of the ink intake port 31 is large, the ink intake port 31 is provided at a position away from the ink supply port 8, and when the size of the ink intake port 31 is small, the ink intake port 31 is provided close to the ink supply port 8. At this time, a method may be used in which the distance between the ink intake port 31 and the ink supply port 8 is set so as to be within 10%.

  In this way, the size of the ink intake port 31 is arbitrarily selected, and the distance between the ink intake port 31 and the ink supply port 8 is appropriately selected, and the distance between the ink intake port 31 and the ink supply port 8 is selected. By arranging them so that the difference between them is within 10%, the flow condition (speed, flow rate) of the ink supplied to the ink reservoir 10 can be made substantially uniform. Accordingly, the ink is supplied almost uniformly to the pressure chamber 6 through the ink supply port 8. That is, the ink speed and the ink flow rate when ejecting the droplets 23 from the nozzles 21 can be easily set, and a satisfactory droplet ejection head 1 can be provided.

<Modification 2>
In the second embodiment, the ink intake port 31 has a predetermined elongated hole shape (length, width), but the present invention is not particularly limited to this. For example, the ink intake port 31 may be arranged by using a long hole having a different shape by arbitrarily changing the length and width. Here, when the characteristics (viscosity, etc.) of the supplied ink change, when the ink is low viscosity, the length and width of the long hole shape are narrowly provided. Conversely, when the ink is high viscosity, You may make it the structure which provided the length and width of the long hole shape widely. Moreover, you may make it the structure where a circular hole and a long hole coexist.

  In this way, even when the characteristics (viscosity, etc.) of the supplied ink are changed, a method in which the shape of the elongated hole (length, width) of the ink intake port 31 is arbitrarily changed, or a circular shape is used. By adopting a method in which holes and long holes are mixed, the flow of ink supplied to the ink reservoir 10 can be controlled to be almost constant, so that the ink passes through the ink supply port 8 and enters the pressure chamber 6. Almost evenly supplied. Accordingly, it is possible to provide the droplet discharge head 1 according to the characteristics of the supplied ink.

<Modification 3>
Further, in the second embodiment, a method in which the long hole-shaped ink intake port 31 is arranged at one place is adopted, but the present invention is not particularly limited to this. For example, a plurality of long hole-shaped ink intake ports 31 may be arranged. As a method of arranging a plurality of ink intake ports 31, a plurality of ink intake ports 31 may be arranged in a direction parallel to the arrangement direction of the supply ports 8. A plurality of supply ports 8 may be arranged in a direction orthogonal to the arrangement direction of the supply ports 8.

  In this way, the same kind of effect as in the second embodiment can be obtained, and by arranging a plurality of long hole-shaped ink intake ports 31, the flow rate of ink supplied to the ink reservoir 10 can be increased. Will be able to supply. Therefore, the ink is supplied promptly and almost uniformly to the pressure chamber 6 through the ink supply port 8. Accordingly, since the ink is supplied to the pressure chamber 6 in a short time, it is possible to provide the droplet discharge head 1 that can discharge the ink droplets 23 at a high speed.

FIG. 3 is an exploded perspective view illustrating a part of the droplet discharge head according to the first embodiment. Sectional drawing of a droplet discharge head. The top view of a droplet discharge head. The perspective view which shows the structural example of a droplet discharge apparatus. The disassembled perspective view which shows a part of droplet discharge head of 2nd Embodiment. The top view of a droplet discharge head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Droplet discharge head, 6 ... Pressure chamber, 8 ... Ink supply port, 10 ... Ink reservoir, 21 ... Nozzle, 31 ... Ink intake port, 100 ... Droplet discharge device

Claims (5)

By superimposing the first substrate and the second substrate on each other, a pressure is disposed between the first substrate and the second substrate corresponding to each of the plurality of nozzles ejecting the liquid, and the liquid is ejected from the corresponding nozzle by pressure fluctuation. A chamber, a reservoir for supplying liquid to each pressure chamber, and a plurality of liquid supply ports for communicating each pressure chamber to the reservoir are partitioned and formed in a state of being arranged in a plane direction. In a droplet discharge head having a liquid intake for injection,
A droplet discharge head, wherein a plurality of the inlets are provided so that a difference in distance between each liquid supply port and a liquid inlet closest to each of the inlets is within 10%.   2. The droplet discharge head according to claim 1, wherein the liquid intake ports are arranged at least in a straight line. By superimposing the first substrate and the second substrate on each other, a pressure is disposed between the first substrate and the second substrate corresponding to each of the plurality of nozzles ejecting the liquid, and the liquid is ejected from the corresponding nozzle by pressure fluctuation. A chamber, a reservoir for supplying liquid to each pressure chamber, and a liquid supply port connecting each pressure chamber to the reservoir are partitioned and formed in a state of being arranged in a plane direction, and the liquid is injected into the reservoir A liquid droplet ejection head having a liquid intake port, wherein the liquid intake port has an elongated hole shape and is formed so that a difference in distance from each liquid supply port is within 10%. Discharge head.   4. The liquid droplet ejection head according to claim 3, wherein the liquid intake port is provided so that a longitudinal direction thereof is parallel to an arrangement direction of the liquid supply ports. . A droplet discharge apparatus comprising the droplet discharge head according to claim 1.

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